Snowboarders feared trapped after avalanche
Rescue teams searching near Sundance, Utah
(CNN) -- About six snowboarders were missing after an avalanche swept down a cliff in Utah and possibly buried them, a sheriff's spokesman said Friday.
A seventh snowboarder dug out, but authorities were still searching for the others as night fell and temperatures began to fall from the high 20s, said Deputy Dennis Harris of the Utah County Sheriff's Office.
The avalanche occurred in the Aspen Grove area outside Sundance.
Authorities were alerted to the incident around 5 p.m. (7 p.m. ET), when a man crossing nearby on snowshoes called 911 and said he saw the avalanche.
"He said there were approximately seven kids that were up there snowboarding when the avalanche had gone down," Harris told CNN. "He couldn't see them any more."
The avalanche occurred during a day of heavy snowfall, about three miles outside Sundance, he said.
"A lot of kids go up there, and they love to snowboard there."
Harris said he did not know if the snowboarders were in a restricted area.
"We have some of our guys checking into that right now," he said.
Rescuers from Utah County and adjacent counties joined the search.
"I'm hoping that it's not going to be as bad as it sounds, but we're very concerned," Harris said.
Conditions were so treacherous that helicopters were not allowed to join the effort, he said.
"They've restricted some of the officers from using their sirens up in the canyon because of the avalanche danger ... the avalanche danger is extreme," Harris said.